Sofa



FIG. 1 shows a perspective view of a sofa showing my new design;

FIG. 2 is a front elevation thereof;

FIG. 3 is a left side elevation thereof;

FIG. 4 is a rear elevation thereof; and

FIG. 5 is a top plan view thereof.

The right side elevation of the sofa is substantially a mirror image of the left side elevation. 

The ornamental design for a sofa, substantially as shown and described. 